(1) Field of the Invention
The present invention relates to a method of inspecting tape creases to be effected at a step for inspecting and adjusting the tape crease condition in the manufacturing of video decks, an apparatus therefor, and an adjusting apparatus using the method.
2. BACKGROUND ART
A conventional tape crease inspecting method, and the inspecting and adjusting apparatuses therefor, will be described with reference to the drawings.
FIG. 12 is a diagram showing the construction of crease inspecting and adjusting apparatuses using a tape crease detecting means with conventional moire stripe processing. FIG. 13 is a view showing a condition of the light projected onto the tape by a tape crease inspecting and adjusting apparatus as shown in FIG. 12.
In FIG. 12, 1 is a projector, 2 is an image pickup apparatus, 3 is a diffraction grid for causing moire stripes, 4 is tape, 5 is a picture processing apparatus, 6 is an actuator control apparatus, and 7 is an adjusting actuator for adjusting the creases of the tape.
In FIG. 13, 8 is a moire stripe projected onto the tape 4 by the diffraction grid 3. 9 is reflection light from the deck (not shown). 10 is a central line of the moire stripe 8. 11 is a straight-line approximation of the moire stripe 8. 12 is the displacement with respect to the straight-line approximation 11 of the moire stripe 8.
In FIG. 12, the light from the projector 1 passes through the diffraction grid 3, and is cast as the moire stripe onto the tape 4. The cast light is introduced by the imaged pickup apparatus 2 to effect the crease inspection of the tape 4 by the picture processing apparatus 5. A judgement standard for the creases of the tape 4 is the size of the bending of the moire stripe and the bent stripe. In FIG. 13, the size of the bending of the moire stripe is given in a maximum value in the displacement 12 with respect to the approximately straight-line 11 of the moire stripe 8. Also, the position of the bent stripe is given in the position of the displacement provided as the maximum value. In this manner, the condition of the creases is discriminated by the picture processing apparatus 5 so as to effect the inspection of the creases. When the crease of the tape 4 is not appropriate, through the results of the inspection, the actuator control apparatus 6 moves the adjustment actuator 7 so as to effect the adjustment of the creases. Thereafter, the inspection adjustment is repeated until the crease becomes appropriate in condition.
But, in the method of casting the light onto the tape 4 through such a diffraction grid 3 as shown in FIG. 12, the reflection light 9 from the deck is also cast, as shown in FIG. 13. The moire stripe 8 cast onto the tape 4 by the projector 1 is worse in contrast, with the boundary between the moire stripe 8 and the tape 4, which becomes the background, being ambiguous.
Due to the items described above, the picture pickup by the image pickup apparatus 2 is not in good condition. Also, a complicated picture processing algorithm is required to calculate the maximum displacement amount with respect to the straight-line approximation 11 of the moire stripe 8 by the picture processing apparatus 5. Accordingly, the inspection time of the crease takes about several tens of seconds in the apparatus shown in FIG. 12. This speed is not practical. Also, in order to detect the crease condition of the running tape, it is required to detect the dynamic changes in the crease of the tape. To detect it, the detection time of the crease must be short.
Further, as shown in FIG. 12, the diffraction grid 3 has to almost adhere on the tape 4, and this positioning is difficult to effect.
Further, in the discrimination of the crease, the condition changes in very small creases are complicated. The condition change is not determined by the maximum displacement amount with respect to the straight-line approximation 11 of the moire stripe 8, but only by the position thereof. Namely, the characteristic amount of many more creases is required to be extracted, and also, a plurality of characteristic amounts are required to be matched properly with respect to the condition changes in complicated creases.
Further, the condition changes in very small creases are complicated, and the quality standard of the crease condition has to, at present, depend upon human physical judgement. Namely, the discrimination result of the crease is required to correspond to the human physical judgement.
Further, as the change condition of very small creases cannot be detected properly in the apparatus shown in FIG. 12 due to the above described items, it is difficult to adjust the crease of the tape quickly and properly with the condition of the crease detected by the use of the apparatus.